Extreme value and cluster analysis of European daily temperature series

Time series of daily mean temperature obtained from the European Climate Assessment data set is analyzed with respect to their extremal properties. A time-series clustering approach which combines Bayesian methodology, extreme value theory and classification techniques is adopted for the analysis of the regional variability of temperature extremes. The daily mean temperature records are clustered on the basis of their corresponding predictive distributions for 25-, 50- and 100-year return values. The results of the cluster analysis show a clear distinction between the highest altitude stations, for which the return values are lowest, and the remaining stations. Furthermore, a clear distinction is also found between the northernmost stations in Scandinavia and the stations in central and southern Europe. This spatial structure of the return period distributions for 25-, 50- and 100-years seems to be consistent with projected changes in the variability of temperature extremes over Europe pointing to a different behavior in central Europe than in northern Europe and the Mediterranean area, possibly related to the effect of soil moisture and land-atmosphere coupling.     

Two-tailed asymptotic inferences for a proportion

This paper evaluates 29 methods for obtaining a two-sided confidence interval for a binomial proportion (16 of which are new proposals) and comes to the conclusion that: Wilson's classic method is only optimal for a confidence of 99%, although generally it can be applied when n≥50; for a confidence of 95% or 90%, the optimal method is the one based on the arcsine transformation (when this is applied to the data incremented by 0.5), which behaves in a very similar manner to Jeffreys’ Bayesian method. A simpler option, though not so good as those just mentioned, is the classic-adjusted Wald method of Agresti and Coull.     

How Objects Believe for Us: Applications in Organizational Analysis

This paper analyzes the concept of belief in contemporary organizations. Most studies tend to envisage belief as something internal to the thinking and feeling person. We argue, however, that belief does not only reside ‘inside’ the individual subject but also in an external economy of objects and rituals. What we call the ‘objectivity of belief’ highlights how various things such as commodities, artefacts, machines and even other people may believe in our place. We develop these ideas by drawing on a rich tradition of social theory that includes Marx and ?i?ek, and apply it to the study of objects, belief and power in contemporary organizations.     

A note on “Re-examining the law of iterated expectations for Choquet decision makers”

This note completes the main result of Zimper (Theory and decision, doi:10.1007/s11238-010-9221-8, 2010), by showing that additional conditions are needed in order the law of iterated expectations to hold true for Choquet decision makers. Due to the comonotonic additivity of Choquet expectations, the equation E[f, ν(dω)] = E[E[f(ω _{i, j} ), ν(A _{i, j} |A _i )], ν(A _i )], is valid only when the act f is comonotonic with its dynamic form, that we name “conditional certainty equivalent act”.     

Is Maternal and Child Health Service use a Causal Gateway to Subsequent Contraceptive use?: A Multi-Country Study

The purpose of this study is to examine the relationship between MCH service utilization and contraceptive use in five countries: Bolivia, Guatemala, Indonesia, Morocco, and Tanzania. The analysis is carried out at the level of the individual woman, with contraceptive-use status modeled as a function of: (1) the availability, quality, and packaging of MCH and family planning services; (2) community- and individual-level determinants of health service and contraceptive use; and (3) intensity of prior MCH service use. Data for the analysis comes from DHS data on women of reproductive age linked with data from service-availability surveys. We use full-information, maximum-likelihood regression techniques to control for the effects of unobserved heterogeneity that might otherwise bias our estimates. In three of the five countries (Morocco, Guatemala, and Indonesia) the results of the analysis suggest that the intensity of MCH service use is positively associated with subsequent contraceptive use among women, even after controlling for observed and unobserved individual- and community-level factors. This result lends support to the proposition that, at least in the context of these three countries, the intensity of MCH service per se use does have a “causal” impact on subsequent contraceptive use, even after controlling for factors that “predispose” sample women to use health care services.     

Two Population-Environment Regimes in the Great Plains of the United States, 1930–1990

This paper analyzes factors that affect net migration rates in counties in the U.S. Great Plains between 1930 and 1990, emphasizing the roles of weather (especially drought), environmental amenities, employment, and population, making use of a rich county-level data set. Using a pooled time series model the paper shows that environment is important in population processes, with weather and agricultural change more important in the 1930s and 1940s, and environmental amenities more important in later time periods. The paper provides important insights into how environmental impacts on migration might change over time, and how those changes might be measured.     

The mediating role of work-to-family conflict in the relationship between shiftwork and depression

Abstract

With significant segments of the working population involved in shiftwork, there is the possibility of serious health outcomes. There are two possible pathways to ill health. In the biological pathway the body's circadian rhythms are affected, leading to physiological disturbances and the inability to cope. By contrast, the aim of this study is to elucidate a social pathway by which shiftwork may lead to mental ill health. It examines the mediating influence of work-to-family conflict in the association between shiftwork and depression. Gender differences are also investigated. The sample included 2,931 Canadian respondents with a spouse and at least one child living at home. Close to 28% of respondents were involved in some form of shiftwork. Structural equation modelling supported partial mediation through work-to-family conflict. Further analyses found that mediation was supported in sub-samples of male and female respondents. The results, however, suggest that the experience of shiftwork is quite similar for men and women as no significant differences were found between mediating models. Overall, the findings support the social explanation of the effect of shiftwork on mental health, but they do not rule out other social or biological pathways.     

Inter-firm collaborations and supply chain coordination: review of key elements and case study

Considering the effects of globalisation, the increase of production and energy costs, and the introduction of advanced technologies, companies need to change their way of doing business if they want to stay competitive. One way of doing this is to establish collaborations with suppliers, distributors and retailers, in order to exchange products efficiently and create value for customers. Nevertheless, the structure of the collaboration must be designed carefully and some coordination mechanisms must be implemented to support this way of doing business. In this article, we first analyse: why companies work together, how they should build their partnership, and which strategies they can implement to facilitate coordination of supply chain activities. We then report a case study of collaboration in the forest industry that shows the benefits of implementing coordination mechanisms as well as the necessity of using incentives to better share these benefits.     

On the minimum expected quantity for the validity of the chi-squared test in 2 2 2 tables

A 2 2 2 contingency table can often be analysed in an exact fashion by using Fisher's exact test and in an approximate fashion by using the chi-squared test with Yates' continuity correction, and it is traditionally held that the approximation is valid when the minimum expected quantity E is E S 5. Unfortunately, little research has been carried out into this belief, other than that it is necessary to establish a bound E>E*, that the condition E S 5 may not be the most appropriate (Martín Andrés et al., 1992) and that E* is not a constant, but usually increasing with the growth of the sample size (Martín Andrés & Herranz Tejedor, 1997). In this paper, the authors conduct a theoretical experimental study from which they ascertain that E* value (which is very variable and frequently quite a lot greater than 5) is strongly related to the magnitude of the skewness of the underlying hypergeometric distribution, and that bounding the skewness is equivalent to bounding E (which is the best control procedure). The study enables estimating the expression for the above-mentioned E* (which in turn depends on the number of tails in the test, the alpha error used, the total sample size, and the minimum marginal imbalance) to be estimated. Also the authors show that E* increases generally with the sample size and with the marginal imbalance, although it does reach a maximum. Some general and very conservative validity conditions are E S 35.53 (one-tailed test) and E S 7.45 (two-tailed test) for alpha nominal errors in 1% h f h 10%. The traditional condition E S 5 is only valid when the samples are small and one of the marginals is very balanced; alternatively, the condition E S 5.5 is valid for small samples or a very balanced marginal. Finally, it is proved that the chi-squared test is always valid in tables where both marginals are balanced, and that the maximum skewness permitted is related to the maximum value of the bound E*, to its value for tables with at least one balanced marginal and to the minimum value that those marginals must have (in non-balanced tables) for the chi-squared test to be valid.